This invention relates generally to colloidal solutions having magnetic particles and uses therefor, and more particularly relates to magneto-optical devices employing the colloidal solution.
Colloidal solutions having magnetic particles sometimes referred to as Ferrofluids are known in the art and are used for many purposes, such as the detection of magnetic fields. Devices responsive to magnetic fields measuring the direction and various values of the magnetic fields are called magnetometers. They come in many forms and among them are devices employing these ferrofluids or colloidal suspensions having magnetic particles.
One such device uses a very dense colloidal suspension having magnetic particles to detect magnetic fields from the orientation of the particles in the liquid medium caused by the magnetic field. The suspension is illuminated by a light source and affected by a magnetic field. Light passing through the solution is detected by a photocell directly in line with the light source, thus providing an indication of the influence caused by the magnetic field. In this device the suspended particles have a shutter or "venetian blind" effect to either allow light to pass through when the magnetic field is of a particular orientation with respect to the direction of the light source or to prevent light from passing through the cell when the magnetic field is at some other angle, such as perpendicular to the direction of the light source. The sensitivity and response time of this device is not optimal because of the greater concentration and viscosity of the magnetic colloidal suspension used therein.
Another device utilizing the effect of magnetic fields on ferrofluids is used to produce light polarization. A magnetic field applied to a suspension of ferrite particles causes orientation of the particles in a liquid medium to form in elongated, lineshaped conglomerates, which polarize incident light passing through the magnetized suspension.
The effect of an electrostatic field on a colloidal suspension consisting of non-magnetic particles is also employed for other purposes. One such device is used for particulate analysis of an air sample. In this device airborne particles are illuminated and subjected to an electrostatic field. Scattered light is detected by a photocell to provide an analysis of the particles suspended in the airborne sample.
However, none of the above devices teaches nor discusses use or adaptability of the effect of magnetic fields on a colloidal solution of magnetic particles for the visualization, detection and measurement of magnetic fields by means of the Tyndall Effect in a particular direction hereinafter called the Directional Tyndall Effect.